Disclaimer: I don't own anything in the Who-verse. That honour belongs to RTD and the mighty and glorious BBC. The only thing I get out of this is a warm fuzzy feeling knowing I am trying to put right what once was wrong.

Author's Note: Firstly I just want to thank everyone who has reviewed, story alerted or made Purpose a favourite story. You guys rock. This chapter is a bit of a monster both in length and in difficulty to write. I hated doing what I had to do in this chapter to Donna and Jack but it has to happen for the remainder of the story to happen...

Chapter XIX

Gwen was first into the Hub the following morning. A hurried ring round her colleagues the previous evening had established that Gwen should check out the lay of the land before anyone else came in. As it turned out, Jack was long gone before Gwen's car pulled into her parking space. Inside the Hub she raced to the computer to check the recordings for the Hub's security cameras. As she expected she was greeted by nothing more than four hours of static. Whatever Jack had done during that long, lonely night he didn't want anyone to know. With a sigh she crossed the Hub to her desk. As she approached she saw a white envelope propped up against her monitor. Impatiently she tore open the envelope and drew out the paper inside.

Gwen,

I can't be here. I need to spend some time with Donna and Siân while I still can. I need you to arrange this death for me. I don't want to know exactly when it will be, or where. Just give me two weeks. The only thing I ask is that Siân isn't there when it happens and I get chance to say goodbye to Donna.

I know it isn't fair to ask this of you. I know you'll tear yourself up with guilt, but I don't think I can do this alone. You are the only person I trust to do this.

Jack.

Gwen's knees buckled under her and she sank into her chair with a shuddering breath. How could he ask her to do this? It was as good as murder. She'd done some questionable things in her time with Torchwood, morally questionable if not downright amoral. But each time she had placated her conscience with the thought that it was for the greater good. If she were honest, this act was no different. It was for the greater good. Donna's greater good. But deliberately killing Jack, even though she knew he would come back to life? That was crossing a line that, once stepped over she would never be able to take back. She remembered the guilt and despair on Owen's face when he had shot Jack, not knowing of his immortality. Owen had lost something in his eyes that day which had never come back, even after Jack had returned and forgiven him. A part of his soul. The difference was, she realised, that if she didn't carry out Jack's wishes, he would never forgive her. And losing Jack's trust would be infinitely more painful than losing that fragment of her soul. Like him, she didn't have a choice. Not if she wanted to remain at Jack's side.

She looked up as Martha stepped into the Hub. Hurriedly she replaced the paper in the envelope and stuffed it into her bag. She would shoulder this burden alone.

"He's not here," she called, astounded at how calm her voice sounded. "He's gone home."

Martha didn't reply, merely nodding to acknowledge Gwen's words. It was selfish, but secretly she was glad that she didn't have to look into Jack's anguished eyes.

Jack drove back to London with the radio blaring out Radio 1, a station he would never normally listen to. The loud thumping music distracting him from his fevered thoughts. It was Tuesday; Donna and Siân would both be at school, and while he was now anxious to see them, eager to grasp every precious remaining moment, he found himself driving to Chiswick. He pulled up outside Donna's mother's drive and got out. He knocked on the door tentatively, unsure of whether he wanted his knock to be answered or not. After a few moments, the door swung open to reveal Sylvia,

"Jack!" she greeted him with a easy smile. "What are you doing here in the middle of the day?"

"Hello Sylvia." Once, soon after the wedding, Jack had tried calling Sylvia 'Mom'. The glacial disapproving look which had descended across Sylvias' features had been enough to convince him never to try it again. "My meeting in Cardiff was cancelled," he lied, forcing a smile on his face. "Since Donna and Siân are both at school I thought I might see if Wilf wanted to go out for a pint."

"He's up on his allotment," Sylvia explained with a grimace. "I don't know why. It's not as if he really grows anything and he can't do any stargazing at this time of day."

Jack gave a genuine smile. He knew exactly why Wilf trekked up to the allotment every day.

"I'll go find him," he said. "Can I leave the car here?" As Sylvia nodded he leaned forward to give her a kiss on the cheek. "Bye."

Somewhat surprised Sylvia kissed Jack's cheek in return. "Bye Jack. Take care." She thought she saw Jack's mouth fleetingly twist in bitterness but almost immediately it was replaced by his wide charming smile. "And if you see Dad tell him to get me some spouts on his way home. We're having shepherds pie for tea."

"Sprouts. Shepherd's pie. Got it." With that Jack turned on his heel and started to stride up the street in the direction of the allotments. He was relieved Wilf was out of the house. The conversation he was about to have with him was not one he wanted with a audience.

"Wilf?" Jack shook the old man's shoulder gently. He had arrived at the allotment to find Wilf, bundled up against the cold in a red wool hat and scarf, asleep in a deckchair, flask by his side. Jack would put money on the flask containing whisky, Wilf's favourite tipple, rather than hot tea.

Wilf stirred, sleepily raising his head to look Jack in the eyes. His face lit up at the sight of Jack but quickly fell when he saw the expression on Jack's face.

"What is it boy? Is it my Donna? Or Siân?" Wilf's voice trembled with fear and Jack immediately felt contrite for worrying him unnecessarily.

"No. They're fine, Wilf. Honestly." He tried to smile reassuringly, but by the continuing look of fear on Wilf's face he knew he wasn't doing a very good job. "It's not Donna, or Siân, or the Doctor..." he said quickly, answering what he knew would be Wilf's next question. "It's me." He saw a momentary flash of relief cross Wilfs' features which was immediately replaced by concern. He knew that Wilf cared for him, and was touched by his concern, but he knew that in Wilf's heart Donna and Siân would always come first.

"You better sit down then," Wilf said practically. "There's another chair in the shed."

Jack fetched the blue and white deckchair and set it down next to Wilf, struggling for at least a minute to assemble it correctly. Looking at the great Jack Harkness battling valiantly with a piece of garden furniture before he sank down into it, Wilf had to smile. He looked so incongruous sat there, coat pooled around his ankles. He handed the flask to Jack, who unscrewing the top poured out a measure of what indeed smelt like whiskey. He knocked it back with a single gulp. Wilf watched him in silence, waiting for him to speak. He sensed Jack needed to do this on his own, without prompting, when and only when he was ready.

After a good two minutes of silence Jack looked at him.

"I've got to leave." He waited, offering no more information. Eventually Wilf spoke.

"For good?"

"Yes." A single word and yet Wilf could hear all the pain he knew Jack must be feeling.

"Why?" For whatever reason Jack had made this decision Wilf knew it wasn't one he would have taken lightly. In the years since Jack had entered Donna's life Wilf had quickly come to see that his original warning had been unnecessary. Jack would never consciously do anything to hurt Donna, or Siân, unless there was no other way. Suddenly he remembered a conversation with the Doctor, long since past, about Siân questioning Jack's lack of ageing. "This is to do with you being immortal," he said quietly.

"The doctor came to see me yesterday," Jack said nodding. "He said that if I didn't leave Donna soon she would start to remember her time with him and that she would, as he put it, burn up. There's no way I can let that happen. So I have to leave before it does. Please believe me if there was any way I could stay I would." Jack's voice was pleading, urging the old man to understand.

Wilf put out a reassuring hand, patting Jack's arm. "I know that Jack. I've known this was coming for some time. Don't worry about Donna and Siân. I'll make sure they're alright."

"The truth is, I'm not just going to leave. That would hurt Donna too much. She would think I wasn't happy or that she'd done something to drive me away. Then she might come looking for me. I'm going to have to die. Very publicly and accidentally so there's no way she can think that me leaving is anything but fate."

Wilf now looked at Jack in shock, "But she'll be devastated. I know how I felt after my Elsie died. I wanted to die myself, there and then..."

"I know," Jack interrupted. "But she'll learn to live with it, just as you have. She'll have Siân and her memories of me will be happy ones, I hope."

"And Siân? Can you really leave her behind without hope that she'll ever see you again?" Wilf already knew the answer to the question, but he had to ask it. Had to hear it from Jack's own lips.

"I don't have a choice. Not if Donna is going to live."

"I'm sorry, Jack," Wilf said finally, his eyes sorrowful. "When are you leaving?" He couldn't bring himself to say the word dying.

"I've got two weeks to make sure everything is in order. After that...sometime soon. It's being arranged. I don't want to know."

"You're a good man, Jack Harkness. God bless you."

Jack didn't speak. He leaned back into his chair closing his eyes and they sat, in silence, as the shadows began to lengthen and the cold autumn sunlight faded.

As Donna walked up the road towards the house she was somewhat surprised to see Jack's SUV already parked outside. She hadn't been expecting him back for another couple of hours at least. She adjusted the heavy bag of books on her shoulder into a more comfortable position and tugged lightly on Siân's hand. Her daughter had, predictably, taken advantage of the momentary pause in their journey to bend over and study what appeared to be the remains of a dead bird on the pavement.

"Come on, Tink," Donna said, reverting back to the pet name she'd used for Siân since she was a baby. "It looks like Daddy is home early."

Siân looked up from her examination, her eyes lighting up as she spotted the SUV. Suddenly she was the one tugging on Donna's hand.

"Come on Mummy. Hurry up." she scolded her impatiently.

With a chuckle Donna picked up her pace allowing Siân to drag her along the pavement to the front gate. Looking across the small yard which passed for a front garden she was further surprised to see Jack sitting on the front doorstep cross-legged.

"Did you forget your key?" she called as Siân pulled her through the gateway.

"Yep," Jack lied. The truth was, his key was exactly where he had put it yesterday morning, in the glove compartment of the SUV. He'd just wanted to see them come home, see the light in their eyes when they found him there waiting for them. He wasn't disappointed.

Donna detected a note of tension in Jack's tone and the way he seemed to be holding himself very still, despite his apparently nonchalant pose, as if he might shatter if he dared to move. She braced herself for the moment when Siân, full of the kind of exuberance only a six-year old can process, threw herself at her father, breathing an inward sigh of relief as she saw his arms relax to wrap the little girl in a bear hug.

"Did you have a good day at school, sweetheart?" Jack asked giving her a kiss on the nose. Donna noticed he had not released Siân from the hug but was clinging on almost in desperation. There was something wrong; something he was trying hard to hide from them.

Siân wriggled to free herself from the hug, then with a grin that was an exact copy of Jack's she plonked herself heavily on his knee. Jack gave an artificial groan of protest.

"Yes. Miss Claythorne said she wanted to put me in for the exams in the summer."

Jack met Donna's eyes over Siân's head. They had discussed this, the need to balance Siân's ferocious need to learn with their determination to give her as normal a childhood as possible. And so whilst encouraging her to learn subjects at a level far above her peers, they had emphasised the need to play. They had been reluctant to give her the stress of exams so early in life. What they hadn't reckoned on was Sian's impatience to absorb more and more advanced knowledge. Their initial fears that Siân would cease to be their little girl had seemed to be unfounded, her ability to switch between intelligent and intensely motivated student and Bratz-obsessed mischief maker at the drop of a hat being almost eerie. Indeed Jack had discussed with Gwen on a number of occasions how like a certain Time Lord she seemed in that respect. Now of course, he thought bitterly, he knew the reason why. Clearly more than just intelligence had been passed to Siân. However much the Doctor protested, he clearly was, in the biological sense of the word, partially her father, or should that be mother since the DNA came from Donna. Jack didn't care; he just knew that at that moment he resented it. Not Siân, never Siân, but the Doctor's role in her creation.

"What do you want to do, Tink?" Donna asked, abruptly bringing his attention back to the present. She sat down beside Jack on the doorstep glaring at him pointedly until he shuffled along to make room for her by his side and dropping the heavy bag onto the flagstones with a dull thud. Jack put one of his arms around her shoulder drawing her close to his side. One arm around each of his two girls.

Siân appeared to consider the question.

"Well, if I do the exams, Miss Claythorne says she can start teaching me lots of new stuff. I'd like that. Please can I do them?"

Donna looked sideways at Jack who shrugged, telling her he was fine with it if she was. He wasn't going to stand in the way of his daughter's ambitions. Learning made her happy. He wanted her to be happy. It was as simple as that.

"Alright then," Donna said, wagging her finger at Siân, who was grinning like a Cheshire cat. "I'll talk to Miss Claythorne in the morning. But this doesn't mean you can give up gymnastics or dance class. You can't spend all day buried in a book."

Siân gave her mother a scornful look. "Why would I give up dancing Mummy? It's fun. Besides Katie says it's the one thing she can beat me at. I'll just have to keep practising! Can I go to Katie's after tea? She's got a new DVD. High School Musical 2. I promised I'd go and learn the dances with her..."

"If you like sweetheart," Jack replied before Donna could answer, earning him a hug. "Come on let's go in, it's getting cold out here."

"Katie's mum says if you sit on cold stones you'll get piles," Siân commented loudly.

Donna looked scandalised but Jack laughed,

"Katie's mum is a very wise woman," he said clambering to his feet whilst still not relinquishing his hold on Siân.

Hours later after Siân was long in bed, Jack and Donna sat on the sofa, Donna laid back surrounded by Jack's arms, watching some crappy Sci-Fi program on TV. Donna loved Sci-Fi but Jack normally stalked from the room whenever it came on with a snort of derision of how unrealistic it was. Donna had argued with him about it,

"It's Sci-Fi. Science Fiction. Fiction being the operative word. It's not supposed to be realistic."

"It's complete bollocks!" Jack had retorted. End of argument.

Tonight though, Jack had said not a word, not even when the hero of the piece had done a time reset manoeuvre which even Donna had to admit was a bit of a cop-out. Tonight he had sat silently, occasionally tightening his grip round her as if he were afraid she might move away. Not that she would, these nights when they sat quiet, just the two of them, were some of her favourites. But it was just one more thing that told her something was wrong.

"Jack. What's the matter?" she asked softly.

Jack seemed startled. "Nothing" he said quickly.

"Don't lie to me, sunshine!" Donna twisted round so she could look into Jack's face, see his expression. "It couldn't be more obvious if you were going around with a big sign saying 'I am upset' stapled to your forehead. Talk to me Jack, please."

Jack sighed and tried to school his features into a placid mask.

"Really, it's nothing. I got a weird feeling today, like someone walked over my grave. I just needed to see you both, make sure everything was alright. It's just left me feeling a bit...off. I'm sorry, I didn't mean to worry you."

Donna reached up to kiss him gently on the mouth.

"Jack, Siân and I aren't going anywhere."

Jack felt his stomach turn but he forced himself to smile.

"I know."

Donna looked at him for a moment, then pulled herself out of his embrace and got to her feet. Reaching across to the coffee table she grabbed the remote and switched off the TV with a flourish, then turning she held her hand out to Jack.

"Come on," she said with a wicked smile, "I know the best way to prove to you that everything is fine. I'll take you upstairs and have my wicked way with you..."

Jack's face crinkled in what Donna could see was now a genuine smile.

"Done!" He grabbed her hand and she pulled him to his feet, then before she could protest he swung her up into his arms. "But first I'm going to have my wicked way with you!"

The following fortnight was strangely the happiest two weeks Jack could remember. During the day, when Donna and Siân were at school, he had meetings with the government, ensuring that they would be provided for and that Siân would never be exploited because of her parentage. He lived every day with Donna and Siân as if it were his last, going to the pictures, bowling, chasing Siân around the adventure playground. Every day Jack took every opportunity to make memories with Siân terrified that she would forget him even though rationally he knew that Donna would never let her forget her father. But he wanted her to have real memories of him, of them all as a family; not just some character her mother told her about, dimly remembered with nothing more than slight affection. Reading her stories at bedtime just so they could laugh together; flying kites on the beach; eating apple pie in the diner where Jack had kissed Donna properly for the first time in the knowledge he might lose her. Each memory a protection against his greatest fear - being forgotten.

Donna wondered at it. Seeing Jack's frantic efforts to be the perfect husband and father worried her. He was afraid. She hoped that it was merely the after effects of his strange feeling, certainly it had all started that day, but her intuition told her it was more than that. Whatever it was she wished Jack would talk to her about it. Whenever she asked him, he would merely turn on the thousand kilowatt smile and deny anything was wrong.

"Jack, we need to talk!" Donna said in a low voice.

Jack looked up from the paper he was reading to catch Donna's warning glance at Siân who was busy trying to finish her cereal whilst reading the back page of the paper Jack was holding. The expression on Donna's face said she was not about to take no for an answer. Jack felt his heart sink. He'd managed to fob Donna off over his strange mood until now, but she could tell something was desperately wrong and he knew she wouldn't rest until she found out what it was.

"What about?" he asked feigning ignorance.

"You know full well. Look Siân's staying at Katie's house tonight, she's having a High School Musical Dance sleepover or something..."

Jack grimaced. He could quite truthfully say that High School Musical was one of Siân's loves he really could do without.

"Why don't we go out for a meal since we've got a night to ourselves?" Donna continued, her expression taking any choice out of the question. "We can go to that Italian on the High Street. I'll be quiet tonight."

"That'll be nice," Jack said trying to sound enthusiastic. "No Tink telling us the principle behind spaghetti twirling."

Siân shot him a dirty look over her spoon which was raised halfway to her mouth. Jack grinned and put his tongue out at her. She returned the gesture.

"Enough," Donna put in, exasperated with the pair of them.

"I'll meet you there after school," Jack suggested. "It's daft you coming all the way back here when it's only five minutes from work." At least he had a day to try and work out a plausible excuse.

"Good idea. I'll get my marking out of the way and meet you there at seven." Donna's face was resolute. It dared him not to turn up. It wasn't an option.

In reply Jack merely nodded and buried his head back into the paper.

He was late. Ten past seven. Donna would be livid. She would think he was ducking out of the confrontation, scared to face her. The truth was, daft as it seemed, he'd fallen asleep on the bed. He'd spent the day trying to think of just the right thing to say to set Donna's mind at rest, but his mind had started to count up the days since the Doctor's visit, since he'd left instructions for Gwen. And he knew that it was only a matter of time. The next thing he had known it had been ten to seven and he had the TV supplement stuck to the side of his face. Hurrying along the road towards the restaurant he shivered, pulling his coat around him to protect himself from the chill autumn wind. Donna would be really mad. She would be waiting outside for him; she hated going into a restaurant alone. She'd be frozen and mad. It was almost enough to make him turn round. He came round the corner onto the High Street and spotted Donna, huddled in the restaurant doorway, her collar turned up against the cold. He could see her mouth moving and realised she was practising all the things she would say to him when he arrived. At that moment she looked up and saw him, her initial expression of relief being quickly replaced by one of annoyance. Jack waved and hurried across the road to join her.

Jack saw the black car come barrelling around the corner out of the corner of his eye, and knew without doubt what was about to happen. He fixed his eyes on Donna and the pavement opposite and continued to cross the road. He saw the horrified comprehension in Donna's eyes almost at the same moment he felt the car strike him, the bones of his legs snapping under the impact sending him tumbling over the bonnet and roof. As he finally came to rest on the tarmac he could hear Donna frantically shouting his name over and over.

Looking up he saw Donna's face blocking the dark sky, her tears falling on his face. She started to lift his head into her lap but, a voice belonging to someone Jack couldn't see commanded her to stop; to wait for an ambulance. Donna shot a look of such vehemence at the unknown individual that the objection subsided, but Donna released his head anyway. Battling the pain which was strafing through his body Jack struggled to raise his head. If these were his last few moments with Donna he wasn't going to let the actions of some interfering, if well meaning, busybody come between them. As Donna became aware of his movement she once again began to raise his head onto her lap.

"Jack, please Jack. Talk to me. Come on baby. Please. Please!" Donna's voice, low and urgent, pleaded for him to reply. He could feel his face wet with tears and he wasn't sure whether they were hers or his. Jack recognised the familiar feeling of his life force slipping away and he fought against it. He had things he needed to say. Things Donna needed to know. He forced his eyes to open and pulled on all his remaining strength.

"Hey sweetheart!"

On hearing his voice Donna cried out, partially in relief.

"Don't move. There's an ambulance coming. Stay with me baby." He could tell Donna was trying to be strong, for him, but her face was distraught. She stroked his face and as her hand moved away Jack realised that the wetness on his face was blood.

"I don't think that's up to me," he croaked, trying to smile at her.

"Don't!" she said leaning over and kissing him tenderly. "You're going to be alright." But she sobbing now, her words distorted. "Don't you dare die on me Jack Harkness. I won't lose you."

"I'll try to oblige, but just in case I just want to say. I love you, I love Siân and I wanted to stay with you for ever."

"Please Jack," Donna shook her head, trying to deny the words she was hearing.

"No I need to say it. I love you and I want you to be happy. Find someone. Find someone to make you happy after... Just like you made me happy." She didn't want to hear this, he knew that. And at this moment he didn't want to say it. The thought of Donna with someone else made him sick to his stomach. But he didn't want her to suffer alone. After Ianto's death she had saved him. It was only right that someone else be allowed to save her. "Promise me,"

Donna couldn't speak. It was unthinkable, loving someone else. She started to shake her head but Jack reached up with a gasp of pain and grabbed the hand stroking his face.

"Promise me Donna. I don't want you to be alone."

Blindly Donna nodded, leaning over to kiss him again, this time fiercely, her auburn hair obscuring the rest of the world from view.

"Please don't leave me alone," she whispered. "Please Jack, I'm begging you."

But she could feel his body go limp, his breathing slow and she knew in that moment that she was going to lose him, forever. It was time. Time to fulfil the promise she had made.

"Jack!" she said sharply. "Open your eyes. Now, Captain!"

Startled Jack opened his eyes to take one last look at Donna, committing it to memory, wishing that his last sight of her was not filled with so much pain for them both. Donna put her mouth to his ear, her last words to him being for him alone.

"I love you. I will always love you. Siân will always love you. And we'll be alright. I promise. Someone else loves you too; and he's waiting for you, Jack. Tell him I thank him with all my heart for letting me borrow you for a while."

Jack's eyes widened at her words and Donna gave a small sad smile. Then she kissed him once more as his breath slipped away.

Only then did she start to scream.